A sticker on the input jack will tell you what speaker the cab was supposed to come with. If it say EV 12L it most likely came with the cabinet.
If you absolutely have to know, you can call Mesa with the serial number and they can tell you when and what speaker it shipped with.
From the looks of it, I would say it's a late OEM EV 12L. The vintage label is to designate it's difference from the series II from the early-late 90's.
When EV introduced the series II many many amp manufacturers were not happy with it's tonal changes. EV then made them to the original/vintage OEM
specs again for the amp manufactures, like Mesa so they would not lose business. From my memory, the 12L Series II came with
the black basket and had EV on the dust cover as well as specifying the speaker was a series II on the back sticker. The sticker was used for non OEM sales
and Mesa used their own "Black Shadow" stickers to identify them, but mainly in open back cabinets. If your speaker is original to the cabinet, it would have most likely
only had the MESA Black Shadow speaker if it was an open back. The original OEM's were made with an unpainted/aluminum basket and no
advertising on the dust cover. I don't recall any of them being stamped EVM 12L, but most did state: Electro Voice Inc.-Model 12L OEM TYPE.
Other than the black basket, it appears to be a 12L with the typical 200W parts. Guessing by the codes
I would say it's a mid 1998 and one of the last of the classic 12L's made for guitar. EV stopped making guitar speakers for many years until the 12L BL 300W
reissue and the new 200W Classic.